Solar energy, which can be converted into electricity using photovoltaic devices, is the largest renewable energy source. Solar cells based on inorganic semiconductors can harvest solar energy efficiently but with a high cost. Polymeric solar cells (PSCs) based on the bulk heterojunction (BHJ) architecture are pursued worldwide due to their distinctive potential for fabrication on flexible substrates with large areas, light weight, and solution processability at a low cost. By blending electron-donating semiconducting polymers and electron-withdrawing fullerene derivatives together, a bi-continuous interpenetrating network with a large donor-acceptor interfacial area can endow the active layer with large photovoltaic effect. In the past decade, extensive research efforts by many groups around the world has revealed promising features of PCSs.
Notwithstanding these developments, there continues to be a need in the art for polymer solar cells that exhibit increased solar conversion efficiency.